I couldn’t let something as interesting as the Q-2 pass through my listening room without hooking it up to my Audio Precision analyzer and taking some measurements. I’m kind of happy to say that not only is it built like something from the 1970s, it measures in some ways like something from the 1950s.
Qinpu certainly didn’t fudge the power rating. The Q-2 starts to clip right at 2.5 watts into 8 ohms, at 1.6% total harmonic distortion plus noise). It crosses 1% THD+N at 1.2 watts. Into 4 ohms, it puts out 3.8 watts at the same 1.6% THD+N.
Distortion at 250 millliwatts (10% of rated power) runs 0.41% from 160 Hz to 7 kHz. Above 7 kHz, it drops dramatically. Maximum THD+N occurs at 56 Hz, where it hits 0.58%. An FFT spectrum analysis of the distortion harmonics shows that at lower signal levels the distortion is primarily second-order, suggesting it’s coming from the single-ended tube preamp stage. As the amp goes into clipping, the odd-order distortion harmonics predominate because the distortion is coming mainly from the amplifier IC. (If you have no idea what I’m talking about, read my entertaining “show and tell” on distortion.)
Frequency response is good at the top end; it’s almost flat to 20 kHz. However, it starts to dive at around 100 Hz and it’s down more than -3 dB at 20 Hz. So forget about using the Q-2 to power your homemade 18-inch subwoofer.
Signal-to-noise ratio is unimpressive: -60.4 dB at 250 mW, -56.4 dB at 2.5 W, both unweighted. Crosstalk runs -50 dB to -67 dB above 400 Hz, but it gets as high as -28 dB at 180 Hz. But hey, that’s still better than your turntable can do.
I can’t say the Q-2 delivers any sort of sonic magic, despite the presence of its tube preamp stage. But I can say it delivers something most inexpensive little amps lack: cool. The TP30 is better, but it’s something of an audio appliance, a practical and unglamorous way to power your speakers. The Q-2 is a product you’ll be proud to own and show off, one that’ll attract attention and admiration when it’s on your desktop playing Pandora from your computer or in your bedroom setting the mood with a little Sade.
Brent Butterworth and Geoff Morrison combine their years of gear testing and knowledge in one überblog of irreverence and techiness.
Copyright © 2013 Bonnier Corp. All rights reserved. Reproduction in whole or in part without permission is prohibited.